


Salt

by marshmallons



Category: Yu-Gi-Oh! Duel Monsters (Anime & Manga)
Genre: Alternate Universe, Angst and Hurt/Comfort, M/M, Prideshipping, Slow Burn
Language: English
Status: In-Progress
Published: 2018-11-08
Updated: 2019-01-19
Packaged: 2019-08-20 12:38:29
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 9,816
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16555922
Author URL: https://archiveofourown.org/users/marshmallons/pseuds/marshmallons
Summary: Seto wondered whether he was really on the beach, in the presence of something unreal, or whether he was still caught in the cold, murky waves even now, writhing in agony and creating the elaborate fantasy of this creature named Atem, who needed him now just as much as Seto needed him too.After a chance encounter with a mysterious creature in a grotto, Seto is forced to reconcile that he's finally lost his mind— or that Atem might just be real, and exactly thethingmissing from his life.[Prideshipping, slow burn, dark themes, mermaid AU.]





	1. Chapter 1

Kaiba stared into the forlorn gray skies and snuffed out his cigarette. 

The black ashes spilled over the brim of the broken bowl that served as an ashtray, which was overflowing with a week’s worth of cigarettes.

He stared at it quietly for a long moment, then raised another to his lips, sparked it, and returned his gaze to the bleak horizon. 

Pale sand stretched out for a mile in front of the bungalow’s paint-chipped porch. Gray waves crashed noisily onto the shore, bubbling and frothing, before receding back into the sea.

Overhead, the cackle and shrieks of the seagulls circling over the stormy waters taunted him, and one particularly loud screech made him recoil with disgust and loathing. 

It was loud and cacophonous and he despised the very birds that circled the skies and always dropped shit over the clean laundry hanging from the clothesline, but above everything else, he resented their awful noise because it wasn’t loud enough to drown out the sound of the waves crashing on the rocks. 

He hated the sea. He hated this town, the prefecture, the entire coast, but he couldn’t leave, not without—

Kaiba checked the time on the delayed watch on his wrist and ignored the tremor in his hands. 

Night was falling and the tides were beginning to rise. It was almost time to go.

Kaiba discarded the remains of his cigarette and returned inside the house. It was just as cold inside as it was outside, and he wrapped his arms around himself tightly as he skulked past the disarray in the living room. 

The last month had been more than he could bear, and his neglect was beginning to show. 

A thick layer of dust covered every surface of the room. There was an empty bottle of red wine on the coffee table and a murky stain on the wooden surface. The halls were dark and empty. The bulbs had long since died, and he had never come around to changing them— he simply wandered in the dark, and he lived like a ghost in his own abandoned house.

The mirrors in the bathroom were cracked and broken, revealing the dull gray backwash in patches where the fragments of glass had fallen out of the frame.

Kaiba stared at his reflection in the broken mirror, studied his own haggard cheeks, the deep, bruise-like shadows under his bloodshot eyes, the inch of unkempt stubble that grew in uneven patches over his chin and jaw. 

He looked like shit. 

_He wouldn’t recognize me like this._

The intrusive thought sobered him at once and it colored his cheeks with shame. 

Kaiba took the dull, unused razor sitting beside the sink and tested it against his thumb, before bending over the sink and splashing icy cold water on his face, too impatient to wait for the old pipes to warm. 

The cold water stung, made him suddenly gasp and sputter, and he snapped out of his lethargic stupor with a violent shiver. Water droplets trickled down to his collarbone and pooled in the hollows of his clavicle as he patted down the counter for an old towel to dry his face. 

When he looked up again, he saw his own eyes, wide and red-rimmed, bloodshot but alert, and he drew himself together long enough to foam his face with plain, unscented hand soap, shaving away the month’s-worth of dark stubble along his jaw, acutely ashamed that he could let himself fall so low. 

The first month had been agony. The sixth month-mark was painful. The tenth month had almost been a return to normalcy. Then it became the twelfth month, and when Kaiba realized it would soon be exactly one year since the accident, the delayed downward spiral resumed.

Kaiba patted his face dry, inspecting his clean, albeit red and irritated face, and ran his fingers through his hair. It was shamefully long now, grown out into a shag that nearly reached his chin at its longest and touched the high apples of his cheekbones at its shortest.

It was too late for a haircut now, but when he tucked the longer strands behind his ears, he could almost pretend he was just overdue for a trim. 

He took one last look in the mirror, and in the poor lighting, his eyes flashed with a resemblance to _his_ , and the jarring reminder knocked the breath from his lungs and drained the color from his face. 

Kaiba bolted from the room, slamming the door behind himself. 

It was time to leave.

* * *

In the harbor, there was a broad array of fishing ships and a motor boat, all of which he owned, but he walked through the sandbar to a small dinghy moored beside a rotting wooden dock. He couldn’t remember the last time he had set foot into it, but it was in desperate need for repair and maintenance, almost pitifully neglected and crusted in a thick layer of sand and salt. 

Two life-jackets still lay at the bottom of the boat, one small and one large. Kaiba took one look at them and averted his gaze, kicking them under the seat, before taking the oars in his hands and beginning to row. 

The salty ocean air whipped his hair into a tangle and it bit at his cheeks, while the pungent scent of briny sea made his nose wrinkle and relieved the tension in his shoulders. Cold water lapped at the sides of the boat with deceptive playfulness, splashing his hands and his face as he rowed meters out into the sea, knowing with calm familiarity exactly where he was going.

Kaiba exhaled slowly and watched the wispy white condensation curl from his lips as his warm breath hit the cold air. The salt dried on his skin and itched uncomfortably, but he ignored the unpleasant sensation and focused soberly on maintaining his direction toward the west, taking care to never drift too far from the coast.

It wasn’t long before the open mouth of the cave came within view, an ominous, gaping black hole that, against the backdrop the dark night sky, looked like a pool of black carved directly out of space. 

He steeled himself, compelled himself to keep rowing, even though he knew it would be easier to hurl himself over the side of the boat and let the waves take him right then and there than to continue rowing. 

The waves gently pushed him into the grotto. 

By the time he docked along the craggy shoals inside the cave, his brow was dripping sweat and his arms trembled violently with exertion. His chest heaved as he panted, lungs burning for air, and his limbs felt heavy when he forced himself to swing his legs over the walls of the small boat, stumbling onto the rocks as he struggled to recover his balance. 

The gravelly sand and barnacles and broken shells blurred together in his vision as he stared at the ground, falling to his hands and knees. 

Mokuba.

The shoals.

_Mokuba._

Tears flooded his eyes and distorted his vision. He stared at the rock beneath his palms, felt his breathing stutter, trapped in the hollow of his chest, and he became eerily silent, not making a single sound as he struggled to suck in gulps of air through his parted lips, until all at once a dry, broken sob poured from his throat, and then he couldn’t stop. 

The tears spilled over his lashes and poured down his cheeks, falling from his quivering chin. Kaiba covered his mouth with a trembling hand and squeezed his eyes shut. 

_Mokuba, be careful-_

_His warning came one second too late. Mokuba’s slight body disappeared from view and he slipped in between the cracks of the rocks with a terrified cry._

_Fear. Adrenaline._

_Mokuba!_

_He screamed violently enough to tear the lining of his throat raw. His feet hit the wet rocks, sharp rocks and fragments of shell carved into the soles of his naked feet, but he didn’t care, couldn’t feel anything past the cold fear or hear anything past the blood racing in his ears and the shrill scream that echoed through the cavernous grotto, and he tasted the sickening metallic tang of blood rising in the back of his throat._

Kaiba’s shoulders heaved with breathless, quiet sobs. His chest felt tight and constricted, overwhelmed with violent grief, and his throat was searing with a painful lump he couldn’t swallow down. His dry sobs slowly calmed into exhausted hiccups, which faded into silence. 

He stared into the dark, murky water with vacant eyes, felt a final hiccup bubble past his chapped lips, and felt raw and empty. 

It was quiet inside the cavernous grotto; the only sound in the echoing through air was the murmur of the water crashing in gentle waves against the rocks. The noise snapped him out of his exhaustion, sent shivers crawling over his skin and goosebumps rippling over his arms, and made his hair stand on end. 

The sound of the sea. He hated it, hated the coast, the water, this grotto, the same place that had stolen the only good thing in his life from him. He was drowning while standing on land, he would never be able to escape the reality that Mokuba was dead, he had to _leave—_

Then, with sudden clarity and peace of mind, he knelt and began to remove his boots mechanically. 

First the laces, untied quickly with surprisingly steady fingers, before he yanked his boots off, gaining speed as he pulled off his socks, balling them neatly and sliding them into the hollow of the instep. He stripped out of his heavy windbreaker, zipping it back up, and folded it neatly, placing it beneath his boots, before he left the safety of the shoal, took a deep breath and a large step forward, and plunged directly into the high tide. 

The cold hit his body like a freight train. It _hurt_ and he gasped, felt the freezing saltwater flood into his mouth and he swallowed mouthful after mouthful. 

He was trapped in the water, the tide cresting over his head and pushing him down over and over again every time he floated to the surface, until his lungs began to burn and he still couldn’t get a breath, couldn’t see past the inky water that swallowed him whole.

His entire body seized, becoming stiff and sinking into the water as every muscle in his body locked and became tense and numb all at once. 

Pain rippled over his skin. The icy water felt like a thousand tiny knives carving into his skin, paring him down to the bone, and it surfaced over his head, drawing him deeper into the terrifying, pitch-black darkness.

For a horrific moment, he wondered if this was the last thing Mokuba felt.

He wondered if it was the last thing he would ever feel.

_It would be easier to sink than to swim._

His limbs were too heavy, his clothing were weighing him down as well, and it wouldn’t be long before his lungs filled with ocean water. 

That would be the end of him. 

In the split seconds he had before the strong tides pulled him to the bottom of the cave floor, he considered letting the water drag him down without a fight.

It would put an end to the cold, to the pain, to the guilt, to the _loss—_

But something inside him pushed him forward, fought past the haze of shock, drove his arms through the water and forced him to claw and drag his way back to the surface, despite the weariness and shock that had settled deep into his limbs. 

A primal instinct inside him was absolutely intent on survival, fought like hell to stay alive, and pushed him to the surface of the water. It was the same instinct that moved his limbs through through the currents, allowed him to pull himself up onto the rocks as soon as they were within reach, pumped the oxygen through his burning lungs, made him cough up the foul saltwater he had unwittingly swallowed. 

Violent coughs and shivers racked Kaiba’s entire body and he curled in on himself, planting his forehead into the crook of his elbow with a pained grunt.

He lay there, miserable and shivering, for what felt like an eternity. His heavily eyelids struggled to stay open and his entire body was weighed down by the oppressive cold and grogginess, but the instinct for survival screamed at him to _stand up,_ to move, to _go home_ before died from shock or hypothermia. 

It would be a bitter tragedy if he died in the same spot as his brother. 

Kaiba stared at his hands through warped vision. His nails were blue and his hands trembled violently, and he knew that he couldn’t stay there any longer. 

_“F-F-Fuck.”_

Kaiba struggled onto his hands and his knees, looked up, and gasped hard enough to set off another fit of coughing. 

A curious face peeked up at him from the water. Wide eyes blinked slowly, one after the other, distinctly not-human, and the lower half of his face was submerged in the water. 

Kaiba felt the hair on his arms raise with fear, not just with cold, and he stared back incredulously, unable to believe— _how the hell could he just float in the water like that, he didn’t understand, how was he breathing with his nose beneath the surface_ — but once he was sure that it wasn’t an apparition — it wasn’t, it blinked in that eerie way again and sidled closer, swimming toward the rocks with alarming speed— Kaiba felt a sudden burst of hot fury warm over the deathly chill in his bones. 

“What are you doing here?” he barked raggedly. The blood rushed in his ears. “Get away from there!”

His voice cracked and trembled, weak after nearly _drowning_ , but it was effective in getting his message across: the strange man recoiled and drew away from the rocks with a guilty expression.

It wasn’t enough; Kaiba’s vision warped, he saw red, and he wanted to do something, he wasn’t sure what, but this was a private place, it was Mokuba’s resting ground, this was part of his own private property, _for fuck’s sake, what was he doing here—_

“Get out!” he shouted again and again, panting breathlessly with fury and exhaustion. “Get out!”

But the man didn’t move. 

Those dark eyes stared at him somberly, his distinctly concerned expression never wavering, until he blinked again in that unnervingly slow way and swam closer. As he closed the distance between them, Kaiba’s livid gaze dropped to the water where his shoulders protruded, and he abruptly noticed with that his upper body was entirely naked.

The question died in his throat when the stranger quietly, but fluidly raised himself onto the rocks. 

Kaiba’s eyes followed the wide set of his shoulders, down the lean, muscled length of his arms, and he realized with rising horror and revulsion that where the line of his torso should end and connect with his hips, there was a scaled fish tail. 

His voice died in his throat. 

Perplexed, he stared, unable to understand what he was seeing. 

When he — _it_ — tilted its head and reached out to touch him, Kaiba recoiled. 

“Don’t touch me,” he said hoarsely, voice scarcely any louder than a whisper. 

He was hallucinating. He had to be. 

Kaiba rolled over and unwittingly planted his face into the rock, hissing at the contact, certain that he had split the skin, though his face was too cold and too numb to be completely sure. 

He heard a wet splash behind himself and when he looked over his shoulder, he saw that the strange creature had pulled his entire body out onto the rocks.

The tail spanned from his narrow hips right down to where his human toes should be. 

It wasn’t real. It couldn’t be real. 

Kaiba squeezed his eyes shut and breathed in short, sharp breaths through his nose, even when the whoosh of cold air stung at his nostrils. 

Home. He needed to get home, out of his drenched clothing, and to recover his core body temperature slowly. He was cold, so painfully cold, that his teeth chattered violently and his skull ached, pounding with a headache. 

Wet fingers ghosted over the back of his hand, and it was all the prompting Kaiba needed to spring down from the rock, hitting the floor with a pained grunt, and to hurry back to the boat as quickly as his unsteady legs would carry him. 

His numb, fumbling fingers couldn’t manage with the buttons of his wet shirt as he yanked it over his head, tugging painfully at his ears, before he threw it on the floor and quickly zipped on his heavy parka. 

He didn’t dare look back, not when he heard that same soft, unusual trill, or when he heard the splash of _something_ entering the water again. He didn’t look back as he rowed out of the grotto, even when he felt eyes glued to his back, and when he thought he saw the faintly iridescent gleam of fish scales through the water, close enough to the surface to reflect the light from the full moon.

* * *

The rest of the return home was a blur, once he was away from the sea and back on land.

He hazily remembered paddling to shore as if in a daze and staggering across the moon-bleached sand with heavy, clumsy footsteps, and suddenly found himself standing in front of his paint-chipped door, staring at the doorknob and fumbling with clumsy, trembling fingers to insert the key and let himself inside.

Once he finally stepped foot inside, he slammed the front door, sagged against it weakly, and realized with astounding clarity that he was _alive_ , felt the blood rushing in his veins and the hunger gnawing at the pit of his stomach, and he was ravenous for the first time in months.

* * *

The next evening, Kaiba convinced himself it was all a delusion.

Sitting at the unused breakfast nook, he nursed a cup of coffee and held a cigarette between two skeletal fingers, staring into the black pool inside his mug and ruminating on what had very clearly been a case of post-shock visual hallucinations. 

There was no way that something had been inside the cave with him.

And even if there had been, there was no way it could have been half-man, half-fish. 

What the hell were those things called anyway?

Mermaids. Mermaids weren’t real, he thought darkly, and his fingers tightened around his mug until his knuckles became white. Maybe it really was time to check himself into an institution. 

The thought made him chuckle humorlessly. He’d sooner die. 

He almost had.

His nose dripped, a miserable post-nasal reminder of his late-night swim, and he sniffled, blowing his nose into a snotty tissue. He could still taste the heavy tang of the salty sea in his mouth every time he swallowed, and it reminded him of the surge of terror and adrenaline he felt in those petrifying moments he spent beneath the surface of the water. 

It also reminded him of the curious creature, and every time that he closed his eyes, he pictured that delicate face and those intelligent eyes and the way it blinked.

As much as he wanted to convince himself that it had all been a hallucination, he couldn’t ignore the unsettling feeling that it had been _real_ , and that there was something inside that cave that wasn’t human.

Kaiba stared at the fading sunlight streaming through the window. The sun was beginning to set, casting beautiful gem-tones over the baby blue waters, and he couldn’t help but wonder if there was something sinister hidden beneath the deceptively beautiful surface of the sea.

He resolved to find out.

* * *

Kaiba waited until the sun had almost entirely disappeared below the pink-tinged horizon to set out in a small motorboat. His limbs still ached from the exertion of the previous night and there was no way that he could bring himself to row to the cave again. 

He docked in the same place as before, close to the mouth of the cave, and stepped safely onto the sand strips that lined the inside. The tide hadn’t yet risen and the water inside the grotto was shallow enough to wade through. Kaiba crept onto the jagged rocks and approached the darker recesses of the cave.

Every hair on the nape of his neck stood on end, and beneath his heavy wool sweater and windbreaker, his arms were covered in goosebumps. 

He was stupid for being afraid of nothing, he thought contemptuously, even as he slipped a hand into the deep pocket of his jacket to reassure himself that he had remembered to bring the heavy steel flashlight. 

His fingers touched the cool metal alloy and it felt weighty and secure in his palm as he drew it out and clicked it on with his thumb. He held it out to light the interior of the cave as he began to look around cautiously, scanning the opaque water and shadowy walls. 

He didn’t have to look far to find the creature again, and this time he was sure that it had to be real. There was no way that he could imagine seeing this _thing_ reclining gracefully on a stretch of sand, just outside the reach of the water.

Kaiba had lived in the fishing village nearly his entire life, but he had never seen a sight like it before. 

His skin was naked and warm, terracotta brown, stretched smoothly over defined muscle that rippled down his exposed arms and abdomen, until the line of his torso ended and the tail began. Two delicate, translucent fins fanned out from his hips, the same warm golden tone as the rest of his tail, which was striped and swirled in intricate swathes of honeyed yellow and orange and white.

Kaiba watched, captivated, by the way it flicked playfully and elegantly along the very edge of the water as the strange man continued to play in earnest with something in the sand, unaware of his presence. 

Kaiba stepped forward without thinking and winced when his foot dislodged a small mound of sand and shells, which caught the other’s attention and made him freeze, looking up sharply, immediately alert. Before he could even blink, the creature was back in the water. 

Already caught, Kaiba stomped forward in his heavy fishing boots, placed one hand on his hip, and accusingly pointed the other.

“So, you’re real, huh?”

The creature tilted his head curiously and sank deeper into the water. Kaiba watched, intrigued, as he drifted low enough for his nose to disappear under the water. There weren’t any air bubbles or signs of breathing as he swam closer, cutting through the water with enviable grace. 

Kaiba dropped into a crouch and peered into the water suspiciously. “What’s the catch? How are you doing that?”

He received a wordless blink, one eye after the other. 

Growing tired of the static silence, Kaiba frowned and sneered, “What the hell’s the matter with you? Can’t talk?”

All at once, the creature’s face brightened and he nodded enthusiastically. 

Oh. 

Seto blinked and sat in contemplative silence for a long moment. He felt those curious, intelligent eyes locked onto his face, and when he looked up, he was stunned to see the creature’s face was a scant few inches away from his own. 

He jerked away by instinct, and guilt flickered across its delicate features. It— _he_ looked ready to swim away, but Kaiba reached out and cried, “Wait!”

“Can you understand me?” he asked warily.

To his surprise, his expression became pleased, and he nodded with a self-satisfied smile. 

Kaiba’s suspicions grew. 

“Then why can’t you talk?” he challenged, and rather than balk at his sharp tone, the creature swam closer to the shore again. 

He touched the slender column of his own throat with delicate fingers, sweeping them down from just beneath the jut of his chin to the dip in his clavicle. 

Before Seto could react, he reached out and touched Kaiba’s throat the same way. It was scarcely more than the faintest brush of soft, damp fingertips against his exposed skin, but Kaiba gasped as if his throat had been clawed open. 

The creature continued gesturing obliviously, and shook his head slowly, emphatically moving his arms in the air to make clear that they weren’t the same. 

Kaiba still hadn’t moved past the peculiar sensation and the warmth those cold fingers evoked, but his working mind readily understood and supplied the correct answer—

“You don’t have the same vocal chords.”

Another bright smile and two curt bounces of his head. Yes, that was right. 

The knowledge wasn’t as comforting as Kaiba thought it would be. However much his mind wanted to rationalize that there was no way the thing in front of him could be anything but a human —it _looked_ like a man, to the extent of his torso— he knew in his bones that he was staring at something unnatural. 

A delicate-fingered brown hand waved insistently in front of his face. Kaiba blinked and looked up, mildly annoyed.

“What are you doing here anyway?” he asked rudely. 

His tone received a frown this time. The boy’s eyes narrowed and his mouth twitched to the side with obvious displeasure, but he gestured for Kaiba to follow him anyway. 

“In case you haven’t noticed, I can’t exactly do that,” he said sarcastically. 

The creature pointed at his galoshes, then used two fingers to pantomime walking across the shallow sandbed. 

“No.”

When he planted his feet firmly into the sand bank and didn’t move, the _thing_ grabbed Kaiba’s knee in a shockingly strong grip and yanked him into the water. 

Kaiba cried out in dismay as he landed flat on his ass and the cold water poured into his boots and soaked his entire lower half. 

“Damn it, what do you want?” 

The creature stared at him stubbornly and gestured at him vehemently to follow. Kaiba huffed angrily and stepped back out of the water, following him from along the coast of the rocks with miserable, resentful footsteps. 

The creature swam beside him in the water, guiding him and watching him attentively. 

Kaiba could feel his eyes glued to his legs, following his every cautious step among the piles of jagged rocks, and he even thought he saw a flash of a _grin_. He was clearly amused by the way Kaiba’s dripping wet pants clung to his legs and the angry scowl that accompanied every stomp of those large feet.

The creature led him deeper into the cave and into an alcove, where he excitedly pointed at what seemed to be a shrine. 

Delicate seashells, pretty, water-blown fragments of glass, and pearls were tucked away into a crevice among the rocks, and Kaiba stared in confusion, unable to understand what he was supposed to be looking at.

Those bright eyes fixed upon him, and he had a sneaking suspicion that he was showing off, perhaps proud of his peculiar collection. 

_Trash_ , Kaiba thought contemptuously, bitterly, but he grimaced politely and nodded. “Nice.”

He ignored the creature’s pout —he clearly knew Kaiba was lying, and he was insulted— and focused on what he wanted to find out. 

“Do you have a name?”

Kaiba sat by the edge of the water, dangling his feet and idly rolling and stretching his ankles, dipping his toes into the gentle waves that lapped against the rocks. The creature watched him with strange fascination, but at the question, looked away from his feet long enough to roll his eyes and nod. 

Kaiba could almost hear him say _of course I have a name,_ and a small smirk twitched at the corners of his lips.

The merman reached a hand out, palm open, expectant. Seto stared at it suspiciously for a long moment, wary that he would yank him into the water again, before extending his own cautiously. 

This pleased him, and he took Kaiba’s hand into his own with surprising gentleness.

Kaiba’s breath hitched in his throat when he felt a nimble finger begin to ghost over his icy cold palm, drawing seemingly nonsensical patterns, until Kaiba focused and realized that he was forming the shapes of letters and spelling something out. His brow was furrowed in concentration, as if he was struggling to remember with careful detail something from memory.

A-T-E-M, he spelled out slowly. A-T-E-M.

“Atem?”

Atem beamed and squeezed his hand in excitement before letting go to point at him, staring at him inquisitively, his question clear, even without speaking. _And you?_

_Seto!_

Mokuba’s shrill voice rang in his ears and Kaiba’s vision blurred at the corners. He averted his gaze and could barely bring himself to choke out his own name.

He didn’t. 

“How old are you?” 

Atem blinked in confusion and gestured again, pointing at Kaiba insistently, but when Seto didn’t still answer, he resigned himself with sad, disappointed nod. 

Atem held up three fingers, gesturing with them twice in the air, then opened his palm to show all five fingers, then used his other hand to hold up nine fingers total. 3-3-5-9. 

He repeated this twice and Kaiba frowned.

“How _old_ are you?” he repeated loudly and stiffly, and Atem glared at him.

3-3-5-9

Seto quickly calculated.

“Twenty?”

A very exasperated shake of his head. Kaiba stared at him and decided that he looked old enough to be twenty. 

3-3-5-9

Atem seemed intent on that number, but Kaiba ignored his antics and sat contemplatively at the edge of the water. 

Out of the corner of his eye, he could see Atem still gesturing adamantly.

3-3-5-9

“Whatever, I get it!” he snapped. 

Atem trilled angrily, and Kaiba had the distinct impression that he had just been insulted. 

They sat in moody silence, Atem acting _shockingly_ human as he crossed his arms tightly across his chest and glared at him ferociously, but in spite of the tension, neither of them made a move to leave the grotto. 

Seto sat with his toes in the water, feeling curiously at ease beside the strangest creature he had ever encountered, and wondered what he was to make of the entire situation. 

He had certainly never encountered anyone like Atem before, and had never even met anyone in the village who needed to use gestures to communicate. 

The quiet was nice, he decided, and snuck a furtive glance over his shoulder at Atem. 

Up close, he could see that his damp hair seemed to have faint streaks of color amidst the deep black, and when Atem sighed, Seto thought he could see the faintest pinpricks of sharp teeth between his parted lips. 

He was so surprised by the discovery that he didn’t notice the subtle shifts in Atem’s posture, the way that his back straightened and his arms fell to his sides, eyes becoming alert and scanning the waters that had been steadily rising the entire time. 

Atem looked over his shoulder and trilled and clicked his tongue insistently, a soft, worried noise, over and over again.

Kaiba stared him without understanding and Atem wrinkled his nose in agitation, before pointing at the water and making sweeping, wave-like motions with his arms, slowly and steadily raising them higher and higher until Kaiba understood that the tides were coming in fast and he needed to get back to his boat.

He nodded, and relief crossed over Atem’s face. He followed Seto back to the place he had docked his boat, which was bobbing in the high tide like a toy in a bathtub, and watched attentively as he carefully crossed the jagged rocks. 

Kaiba tried not to think about Mokuba and focused on placing one foot in front of the other, until he was finally standing on the deck of the small motorboat, and sighed in relief and realized that his knees were knocking together with exhilaration. 

He looked over the side of the boat and spotted Atem floating nearby. Atem looked at him and smiled with a little wave, but kept his distance, clearly wary of the propellers and the engine. 

He was the last sight Kaiba could make out as he sailed out from the grotto, and he stared at Atem’s tiny, waving figure until he became a mere blur in the distance.

* * *

The cold sea breeze ruffled his hair, carrying with it the pungent scent of salt. 

Kaiba tightened his spindly fingers on the blanket draped around his shoulders, shivering beneath it. As he drew in a final drag from his cigarette, he thought about the chill of the water and Atem’s bare skin, the strange collection of crap he was hoarding in the grotto, and the delicate swirls of gold and orange scales on Atem’s tail. 

He exhaled a soft, curling puff of gray smoke from between his lips and wondered what Atem had meant by 3,359.

**Notes for the Chapter:**

> [The grotto.](http://3.bp.blogspot.com/-p9zOQYFZoro/UsCxnQ-ouKI/AAAAAAAAQzA/MDomae9Js_w/s1600/P1010511+Sea+lion+caves.jpg)
> 
> You can thank my lovely friend @nsfwnoses' [beautiful merm au art](https://nsfwnoses.tumblr.com/image/167627588477) for this disaster! 
> 
> Me, chanting @ myself: this isn’t gonna be a slowburn, this isn’t gonna be a slow burn, _this isn’t gonna be a slowb-_
> 
> I really just wanted to write some monster fucking.
> 
> Atem's tail is based on a [lionfish!](https://c8.alamy.com/comp/J2T897/common-lionfish-or-devil-firefish-pterois-miles-often-confused-with-J2T897.jpg)
> 
> Please please please leave a review? Yes? Thank you! I’m very nervous about the direction of this fic and comments are very much appreciated ( ；∀；) ❤️


	2. Chapter 2

**Notes for the Chapter:**

> As always, a comment is very much appreciated ❤

Seto prepared himself to go into the town for the first time in one year. 

It was early in the morning, far earlier than he had any reason to be awake. The sun had yet to loom over the horizon, but he had woken up at the crack of dawn and when he couldn’t fall back asleep, he sat beside the coffee table on the balcony, observing the cresting gray waves and the bleak skies, stormy and forlorn. 

He stared at his hands, wrapped tightly around a lukewarm mug of coffee, and studied the fine lines on his fingers until they blurred in his vision. He couldn’t bring himself to think about leaving without feeling a swell of mild panic in his chest.

Losing Mokuba had been more than he had ever thought he could possibly bear. His resulting isolation had been crafted, deliberate, and it was meant to be permanent.

His groceries had been shipped by a personal assistant for the entire year, dropped on his doorstep without fail every first week of the month. He hadn’t left the house ever since the memorial service for Mokuba, save the occasional walk on the beach when the space in his house suddenly felt too cramped and claustrophobic, overwhelming and too much and not enough, all at once. 

Now, the prospect of leaving the safety and privacy of the coast was overwhelming.

That old, familiar feeling of unease began to bubble underneath his skin. 

Seto pressed his fingers to his temples. His pulse throbbed beneath his fingertips.

_You can’t just stay here forever...you’re gonna have to leave the house sometime, y’know._

The voice ringing in his ears sounded like _him._

Seto stiffened and felt the hair on the nape of his neck stand on end. He stared blankly at the flecks of dust on the table, counting them, until he finally stood, leaving the mug in place, and walked toward the door before he could lose the nerve to leave. 

Almost anything was better than staying alone with his thoughts when they began to sound like him. 

* * *

The ride into town was short. 

Cold, fresh air filled his lungs to bursting and the steady sea breeze tousled his hair as he drove with the sunroof down, listening to the roar of the wind and ocean beside him. 

The skies were dim and gray, misted over with a heavy layer of dense morning fog, and the chill made Seto’s skin crawl. His exposed fingers were dry and tinged red, wrapped tightly around the steering wheel, and a peek in his rearview mirror revealed that his nose and cheeks were equally flushed and wind-chapped. 

His teeth chattered violently in his skull and he felt alert and alive. 

Seto was impressed, above all, that his car still ran without problem. The steering wheel felt familiar and molded beneath his hands, as if no time had passed at all since the last time he had taken the car out for a drive; the engine didn’t purr like before and the motor made a strange noise when he tried to push over sixty, but it got him into town in one piece. 

It had been nearly a year since the last time he had visited, but the town remained virtually the same, untouched by the effects of time and the changing seasons. Small, square houses, painted neat and unoffending neutral hues, roofed with uniform green tiles, lined every scenic street, just as they did the last time he set foot in the sleepy town. Family shops dotted every street corner, and at that time in the morning, when children were in bed and parents were at work, the sidewalks were blessedly quiet and empty, besides the occasional pedestrian or outdoor cat. 

He walked down the unfamiliar sidewalks with his hands in his pockets, feeling small and out of place. 

Seto damn near owned the entire fishing town, paid the salary of every fisherman under the employment of KaibaCorp, and he was well-known and reputable among the townspeople as the adopted son of a deceased business tycoon from the mainland—

But he was also known as the isolationist who had lost a brother and disappeared into a house hidden along the coast without a single word. 

A small golden bell chimed delicately above his head when he pushed open the paint-chipped green door to the bookstore. The room was small and clean, a former living space that had been converted into a shop, and the center of the room was occupied by rows of shelves, neatly packed with various collections of books. 

The sweet scent of incense permeated the room. The sandalwood fragrance was familiar, a scent that had haunted the empty rooms in the mansion for months until it finally faded. 

Seto’s stomach twisted and he suddenly felt that he might become sick. 

He lingered uncertainly beside the door, torn between staying and leaving. 

“Good morning. I’ll be with you in one moment, thank you!”

A wary scan of the room revealed an old man behind the counter. 

Seto hadn’t noticed him at first, but the shop’s owner, a small man hunched over with old age, stood behind the counter with his back toward the main entrance.

Silvery hair was combed neatly over a thinning patch on the back of his skull, and a dainty green apron was drawn into a bow over his narrow shoulders. His back remained turned toward the entrance, and without saying a word, Seto forced himself to step deeper inside the shop.

Seto scanned the aisles of books while he waited. If he could find the books on his own, he could leave quickly, he reasoned, but the longer he searched, the more bewildered he became. The books didn’t appear to be sorted by any obvious order and he wandered aimlessly throughout the store, perusing random titles and pausing to stare, confused, at a book of Japanese folklore sitting between a cookbook and a travel book.

It wasn’t long before the shopkeeper approached. A noisy creak in the floorboards gave away his presence and Seto turned, guarded, and watched the recognition slowly flicker across the old man’s kind features. 

“Oh! Mr. Kaiba…”

Sympathy. It was in his tone and in his eyes, and Seto loathed it.

The shopkeeper patted down the front of his apron and smiled warmly. “Sorry to have kept you waiting. What can I do for you today, Mr. Kaiba?”

His gentle voice was disarming. 

“I’m looking for books on sign language.” 

“Sign language?” 

The shopkeeper adjusted the thin, wire-framed glasses atop the bridge of his nose and tapped his chin thoughtfully with his forefinger. Seto absently noted that the nametag on his breast pocket read _Itou._

“That’s a rare request. I might have one or two books to help you...I’m afraid I just have to remember where to find them. My memory isn’t what it used to be.”

Itou smiled ruefully and gestured for Seto to follow him. 

Seto awkwardly hovered over him, distinctly aware that he towered over everything in the store, and followed him through the columns of uncategorized books until Itou stopped in front of a wall in the back of the shop. 

“Languages, here we are. I have two books, just as I thought, although one of them _is_ for children…”

Seto’s attempt at a smile closer resembled a grimace. 

“That’s not a concern. I’ll take them both.”

Itou walked slowly to the counter. “It’s been a while since we’ve seen you in town, Mr. Kaiba.”

Seto bated his breath and hoped he didn’t expect an answer. Itou’s voice became even softer.

“The anniversary wasn’t too long ago, was it? I sold him a book that morning.” 

Itou smiled sadly. 

“I don’t remember things very well these days, but I remember your brother very well, Mr. Kaiba. Such a nice young boy, very friendly. He came here often.”

The words rang in Seto’s ears. He averted his gaze, fixing it on the bag into which Itou was placing the books with great care. He could hardly hear the rustle of the paper bag over the hollow rushing in his head, and the room suddenly felt three times too small. 

A foreign lump lodged itself in his throat and he couldn’t swallow past it, let alone bring himself to speak. 

“Your total comes out to…”

Itou paused, before his sympathetic tone became mildly panicked. 

“I’m sorry, Mr. Kaiba, I didn't mean to—”

Seto clenched his jaw and threw 6,000 yen onto the counter. It was more than enough for the two books and he caught the faint expression of surprise on Itou’s face in the split seconds before he tore the bag from his hands, turned on heel, and all but fled from the store. 

The anger distorted his vision. The streets became a blur and Seto stormed to his car, throwing the door open and slamming it shut once he dropped into the driver’s seat. 

He braced his palms against the steering wheel and breathed raggedly, panting, almost gasping for oxygen. The air became trapped someplace between his throat and his lungs, suffocating him, and it reminded him of the dreadful feeling of the water pouring into his lungs when he was caught beneath the surface of the sea. 

It wasn’t until he looked up and saw the steering wheel swimming in his warped vision that he realized his eyes were wet. 

“ _Damn it!_ ”

Angry, he pounded his fist against the steering wheel, again and again, until the tendons in his hands ached and he could see the blood pooling dark and ugly beneath the contusions forming on his skin. 

The flood of anger drained out of him and he sagged against the steering wheel. His hand throbbed in his lap. The roar in his ears silenced into a quiet echo. 

Seto placed his key in the ignition and wiped his cheeks with his trembling hand while the engine warmed. 

* * *

Seto pored over his new collection of books on the veranda, reclining on a lounge chair. He sat in silence, only occasionally interrupted by the squawk of gulls and the roar of the rushing waves crashing on the shore, and studied the diagrams and illustrations on each page, becoming familiar with each of them. He mimicked them with his own hands every so often, occasionally almost dropping his cigarette in the process. 

He flipped through the book, looking for phrases that could be useful, and wondered how long it would take for Atem to learn these words— or whether Atem was even capable of learning. 

Seto chewed on the inside of his cheek, eyes lidded at half-mast, and he stared contemplatively toward the coast. 

Atem did have hands, he could remember that much, and he did seem to possess a sort of uncanny intelligence.

For a fish, anyway. 

Seto took a final drag and snuffed out the last of his cigarette as he reflected on the merman’s curious appearance and those bright, alert eyes. He had possessed enough intelligence to communicate with gestures and he had spelled out his name in katakana, which suggested some sort of previous contact with humans, possibly even Japanese sailors. 

Seto still couldn’t shake off the suspicion that Atem was a figment of his imagination, irrefutable evidence of his slow and anticipated descent into madness. But whenever he remembered the sensation of the cool fingertips that had caressed his throat in a way that had been so unintentionally intimate, he couldn’t bring himself to deny that he had _felt_ that. 

Lowering his gaze down to the book spread out on his lap, Seto traced the illustration of a girl’s hands with his index finger, silently reading the text beneath the diagram. 

Vocabulary:  
_How are you?_  
_Same old, the usual._  
_Sleepy._  
_So-so._

 _So-so._ He copied the gesture, a fairly familiar one. Practicing alone in the middle of a private beach in order to potentially speak to a _mythical creature he wasn’t even sure existed,_ he felt distinctly stupid. 

Sobered, Seto sat quietly, observing the horizon. The sun was hidden behind a thick layer of clouds and fog had rolled over the coast, forming an ominous, dense blanket over the sea. 

He caught an unexpected flash of gold from the corner of his eye, blinked, and squinted at the water, scanning the dark, rolling surface of the waves for the same gleam again.

It flashed again, tantalizing, just outside the line of his vision and he turned his head sharply, catching it gleaming again just above the surface of the water. Seto’s curiosity became aroused as it approached closer to the shore. He set his book aside and stood, approaching the rail of the balcony and bracing his forearms against it, squinting out at the sea.

As it drifted closer, dragged in by the tides, Seto felt the hair on the nape of his neck stand on end. He stared in disbelief, watching it take form in front of him, emerging slowly, until he could discern fins and listless arms, an unmistakable torso bobbing in the water. 

He didn’t stop to think; he moved numbly, as if in a haze. His feet carried him mechanically, crossing the five short steps leading down from his porch to the sandbank, and treading through the flat stretch of land that separated him from the sea.

It wasn’t until his bare feet thudded heavily on the packed, damp sand that he became aware he had started running at some point; his breath rattled in his lungs, his chest heaved with exertion, but he continued to run, closing the distance between himself and the sprawled out figure on the beach.

It was Atem. 

Even from a distance, Seto knew. There was no mistaking the brilliant hues of his tail or his warm, bronzed skin. He was a spot of color on the bleak, sandy coast, and as Seto drew closer, he made out the contrast of green fishing nets tangled on the delicate orange fans of his fins.

Atem was strewn across the beach, facing away from Seto, and when he remained unresponsive, Seto had the horrible, sinking sensation in the pit of his stomach that he might be dead.

Seto slowed to a stop, just a few feet away, and he stared at Atem hesitantly, waiting with trepidation— and releasing his bated breath when he finally moved. 

Atem shifted his weight, propping himself up onto his elbows, and picked helplessly at the nets. He was still unaware of Seto’s presence, until a wave sloshed against his ankles with a soft murmur and gave him away. 

Atem turned, jerking his head over his tense shoulder with a guarded, fearful expression that quickly ebbed when he recognized Seto. 

Seto knelt to his height. Atem stared at him with wide, angular eyes. In the daylight, Seto could now see that his eyes were a startling, unnatural shade of maroon. 

Atem didn’t say a word.

“Hey,” Seto said self-consciously. 

As an afterthought, he waved his arm in a half-circle in front of his chest. He strained to remember the diagrams in the book, but he hadn’t yet learned how to ask if someone needed help. 

“...Need help?”

Atem looked at him disdainfully, then tugged at the nets wrapped around his tail, then looked back at him with a stern expression. It wasn’t difficult to imagine a disapproving voice— _this is all your people’s fault._

Seto shrugged. 

“Just be glad you weren’t caught in someone’s net or the pointy end of a harpoon. You could be trapped in some scientist’s display case by now.” 

Atem bristled, but when Seto gestured at the nets and tentatively reached out, grabbing one end with a wary look over his shoulder, Atem nodded and sat patiently.

The nylon nets —two, from what Seto could begin to make out— were caught in a complicated tangle. He sat down for a better look. His thin, long-sleeved shirt didn’t offer any protection from the cold and shivered when the icy water splashed against his back and drenched him, slicking his clothing against his skin. 

Gritting his teeth, Seto pulled at the nets with numb fingers.

Atem tried to be helpful and patient, but Seto could see the flash of pain across his face whenever he yanked too hard, searching for any give to the nylon cords. 

“Wait—”

It quickly became obvious that they were not making any progress. Seto chewed his lower lip and looked around. The coast was clear of people and fishing boats. They were on a private beach, but he was not taking any chances. 

“Stay here,” he instructed.

Atem looked at him sourly. _As if I could move, even if I wanted to._

Seto ignored his unspoken condescension. He began to walk in the direction of the house, but he looked over his shoulder and spotted Atem’s dismayed expression. Something about it compelled him to blurt out, “I’ll be right back.”

He sprinted. 

His stomach clenched when he reached the porch, threatening to spill its pitiful, meager contents all over the sand-swept steps, but he stepped inside the house without pause, panting and folded over. 

Seto hunted through the spartan living room for a switchblade or an old Swiss army knife, rifling through old newspapers and the cluttered mess on his coffee table, cursing himself for the disarray, until at last he located it, hidden beneath an unread book.

With the relief came a sudden surge of cold, and he trembled violently in his wet clothing. He pictured Atem alone on the beach, and he started toward the door on instinct— but another shiver racked his shoulders, and he knew he couldn’t wait a minute longer to get out of his clothing.

Seto stripped as he stalked into the bedroom, yanking his wet shirt over his head and throwing it carelessly onto the floor. It was too cold to wear just anything, and there was no point layering on warm clothing when he was going to step into the waves again, he rationalized, reaching for the wetsuit at the very back of his closet. 

In his haste, he couldn’t stop to think about the smaller, identical wetsuit packed away in the boxes that he still couldn’t bring himself to throw out.

Seto zipped the suit up as far as he could reach, before he snatched the army knife from the floor and hurried back outside. On the porch, he paused and reached for the book on sign language as an afterthought, tucking it under his arm.

The third sprint across the beach burned at his calves and in his lungs. His lungs rattled with every sharp inhale of the chilled, salty air, but it wasn’t long before he reached Atem. 

Seto held up the army knife triumphantly, brandishing it without thinking. 

Atem bared his teeth defensively and Seto froze. 

It was the first time he had really had a clear view of Atem’s mouth. His lips were soft and inviting, but Seto’s eyes skimmed over them and focused on the sharp points of Atem’s teeth. He had never seen a double row of sharp teeth in a human being’s mouth before.

Then he fumed.

“If I had known you have a _mouthful_ of knives, I wouldn’t have needed this,” he growled, breathless. “Hold still. I’m going to cut the net.”

The blade was dull, but it served its purpose. Seto cut through the woven strands, taking care not to scrape the delicate scales or the fins caught in the nets. It was mindless work; he soon drowned out the sound of the waves coasting beside them, preoccupied with trimming the coarse nylon fibers. 

Atem stood carefully still while Seto worked. But every so often, his fins twitched, and the prismatic sheen of his scales caught Seto’s eye. Faint golden veins trailed through the red and orange-hued scales, and he trailed his finger along one before he could stop himself. 

Atem startled at the unexpected touch, and Seto surprised himself. His breath hitched and he exhaled sharply, the vapor of his warm breath curling in the cold air, and pretended that he hadn’t met Atem’s strangely heated gaze afterward. 

He returned to the nets that had fallen away from his straying hands. It took all his concentration to finish cutting away the final tangles of rope, but before he could finish, Atem’s hand reached for his own. 

Unlike before, when his skin had been cold and wet from the sea, his hands were dry and warm against Seto’s numb fingers. Atem turned his hand over, revealing the purpling bruise and dark, palpable veins in his palm. 

His inquisitive gaze burned into the side of Seto’s face. He avoided it, staring intently at his own hand, and he loathed the ugly colors that stood in vivid contrast to Atem’s. Atem traced the veins on his palms with a featherlight touch, just as Seto had done to him before, and simply let Seto’s hand fall away from his own once he was satisfied. 

Confused by the warmth rising to his cheeks, Seto squeezed his hand into a fist, digging his fingernails painfully into the bruise on his palm. The dull ache grounded him and he smiled grimly, before taking the blade back into his hand. He squeezed the slim handle of that too, and if he saw Atem frowning at him out of the corner of his eye, he pretended that he didn’t. 

With one final slash, the tangle of nets came undone. Atem flicked away the loose strands of netting and splashed his fins in the cresting waves.

Contrary to Seto’s expectations, Atem didn’t immediately escape to the safety of the waters once he was freed from the nets. He remained where he was, as if he had become frozen in place, and he stared at Seto with a curiously reverential expression. 

The waves crashed in the silent spaces between them. 

Seto remembered the book he had cast aside at a safe distance from the sloshing waves. He held up a finger before he retrieved it, dusting the sand from between the pages, and returned to Atem. 

“I bought this book to teach you sign language,” Seto explained. “Have you ever seen a book before?”

Atem gave him a withering look and pointed his nose in the air. Seto took that as a very offended _yes_.

“Well, you can start with this one. You can learn to communicate with me by signing.”

Just as soon as the words left his mouth, he realized he had no idea whether or not he would even see Atem often enough for him to have an excuse to learn. 

He hesitated to hand over the book, but Atem reached for it eagerly, taking it from his hands. He turned the pages with reverence and looked at the words on the page curiously. His expression became stricken.

“Can you read Japanese?” 

Seto already suspected the answer. Atem shook his head slowly and made the same gesture Seto had copied from the book earlier: _so-so._

“I’ll read the word, and you can copy the gesture. Then we’ll both know the word.” 

Atem’s face brightened. Seto was vexed by how much pleasure that expression brought him. 

Atem very quickly mastered the rudimentary gestures. They moved on to basic questions, which Atem seemed to understand and responded to with ease.

Seto skimmed over a list of questions and phrases within the text, before he found one worth asking. 

_What do you eat?_

Atem grinned, revealing the sharp rows of his teeth, and made the gesture for _fish_. Ignoring the book, he spread out his hands, indicating a big fish, and pantomimed taking a big bite from the center. The points of his teeth clicked together unnervingly. 

For the first time, Seto felt a cold rush of fear and exhilaration. 

_He’s not as harmless as he looks._

Seto cleared his throat and looked back down to the book in his lap, skimming over the page for another question. Atem leaned over his shoulder to inspect the images and Seto tried not to think about the mouthful of very sharp teeth inches from his neck. 

_Where are you from?_

Atem watched his hands and paused, before pointing toward the sea and swooping his arm out in a large arc enthusiastically, indicating past the horizon. Seto gave him a look and turned to the world map on the next page.

It was mildly amusing to see Atem’s mouth fall open into an obvious _oh._

_Where?_

Seto watched him study the map closely, face drawn tight in concentration. Atem pointed to the Red Sea, trailing his finger closer toward the narrow stretch of the Suez Canal. He lingered over Egypt, drawing his fingers over it in circles, with just a hint of a smile.

Egypt.

Seto stared at the differences in their skin, his own pale, olive-toned hands, contrasted to the rich, warm terracotta of Atem’s hands and torso. It wasn’t too difficult to imagine Atem basking in the warm Egyptian sun. 

He reached to turn the page, but Atem stole it from his lap. Astonished, Seto stretched for it again, but Atem held it to the side, just beyond the reach of his fingertips with a stubborn expression.

Seto forgot all about signing. 

“What do you want?” 

Atem pointed emphatically at his own chest, before pointing back at Seto.

_My turn to ask you a question._

“Fine. What do you want to know?” 

_What is your name?_

Seto licked his lips and stared at him, mouth parted, only mildly surprised. He deliberated for a long moment, staring all the while into Atem’s painfully earnest eyes, before he relented.

“My name is Seto.”

Atem couldn’t speak, but the smile that broke across his face spoke volumes—

And Seto found himself mirroring it tentatively.


End file.
